Protective effect of vanillin on radiation-induced micronuclei and chromosomal aberrations in V79 cells

Do professional painters comprise a high risk group for genotoxicity? A systematic review

Professional painters represent an occupational population group that deserves attention for study in the field of occupational toxicology due to the wide range of complex chemical mixtures they are exposed to. It is imperative to underscore that the International Agency for Research on Cancer has classified commercial painting as a high-risk occupation for the development of cancer. Given this context, the primary objective of the present study was to conduct a systematic review aimed at addressing the following question: are car painters at occupational risk regarding potential genotoxicity? To address this question, a selection process was undertaken, with three reviewers carefully selecting, reading, and analyzing full manuscripts from 26 studies included in this review. The technical rigor of these studies underwent meticulous scrutiny, culminating in the classification of six studies as Strong, eight as Moderate, and 12 as Weak, predicated on the extent of confounders considered. Taken together, the findings suggest that chemical substances from paints may indeed pose a risk of genotoxicity for professionals in this field, as all studies indicated genotoxicity among professional painters through various tests.

Connection between Radiation-Regulating Functions of Natural Products and miRNAs Targeting Radiomodulation and Exosome Biogenesis

Exosomes are cell-derived membranous structures primarily involved in the delivery of the payload to the recipient cells, and they play central roles in carcinogenesis and metastasis. Radiotherapy is a common cancer treatment that occasionally generates exosomal miRNA-associated modulation to regulate the therapeutic anticancer function and side effects. Combining radiotherapy and natural products may modulate the radioprotective and radiosensitizing responses of non-cancer and cancer cells, but there is a knowledge gap regarding the connection of this combined treatment with exosomal miRNAs and their downstream targets for radiation and exosome biogenesis. This review focuses on radioprotective natural products in terms of their impacts on exosomal miRNAs to target radiation-modulating and exosome biogenesis (secretion and assembly) genes. Several natural products have individually demonstrated radioprotective and miRNA-modulating effects. However, the impact of natural-product-modulated miRNAs on radiation response and exosome biogenesis remains unclear. In this review, by searching through PubMed/Google Scholar, available reports on potential functions that show radioprotection for non-cancer tissues and radiosensitization for cancer among these natural-product-modulated miRNAs were assessed. Next, by accessing the miRNA database (miRDB), the predicted targets of the radiation- and exosome biogenesis-modulating genes from the Gene Ontology database (MGI) were retrieved bioinformatically based on these miRNAs. Moreover, the target-centric analysis showed that several natural products share the same miRNAs and targets to regulate radiation response and exosome biogenesis. As a result, the miRNA-radiomodulation (radioprotection and radiosensitization)-exosome biogenesis axis in regard to natural-product-mediated radiotherapeutic effects is well organized. This review focuses on natural products and their regulating effects on miRNAs to assess the potential impacts of radiomodulation and exosome biogenesis for both the radiosensitization of cancer cells and the radioprotection of non-cancer cells.

The vanillin derivative VND3207 protects intestine against radiation injury by modulating p53/NOXA signaling pathway and restoring the balance of gut microbiota

The intestine is a highly radiosensitive tissue that is susceptible to structural and functional damage due to systemic as well as localized radiation exposure. Unfortunately, no effective prophylactic or therapeutic agents are available at present to manage radiation-induced intestinal injuries. We observed that the vanillin derivative VND3207 improved the survival of lethally irradiated mice by promoting intestinal regeneration and increasing the number of surviving crypts. Pre-treatment with VND3207 significantly increased the number of Lgr5⁺ intestinal stem cells (ISCs) and their daughter cells, the transient Ki67⁺ proliferating cells. Mechanistically, VND3207 decreased oxidative DNA damage and lipid peroxidation and maintained endogenous antioxidant status by increasing the level of superoxide dismutase and total antioxidant capacity. In addition, VND3207 maintained appropriate levels of activated p53 that triggered cell cycle arrest but were not sufficient to induce NOXA-mediated apoptosis, thus ensuring DNA damage repair in the irradiated small intestinal crypt cells. Furthermore, VND3207 treatment restores the intestinal bacterial flora structures altered by TBI exposure. In conclusion, VND3207 promoted intestinal repair following radiation injury by reducing reactive oxygen species-induced DNA damage and modulating appropriate levels of activated p53 in intestinal epithelial cells.

Pharmacology of natural radioprotectors

Radiotherapy is one of the most efficient ways to treat cancer. However, deleterious effects, such as acute and chronic toxicities that reduce the quality of life, may result. Naturally occurring compounds have been shown to be non-toxic over wide dose ranges and are inexpensive and effective. Additionally, pharmacological strategies have been developed that use radioprotectors to inhibit radiation-induced toxicities. Currently available radioprotectors have several limitations, including toxicity. In this review, we present the mechanisms of proven radioprotectors, ranging from free radical scavenging (the best-known mechanism of radioprotection) to molecular-based radioprotection (e.g., upregulating expression of heat shock proteins). Finally, we discuss naturally occurring compounds with radioprotective properties in the context of these mechanisms.

The Role of the Core Non-Homologous End Joining Factors in Carcinogenesis and Cancer

DNA double-strand breaks (DSBs) are deleterious DNA lesions that if left unrepaired or are misrepaired, potentially result in chromosomal aberrations, known drivers of carcinogenesis. Pathways that direct the repair of DSBs are traditionally believed to be guardians of the genome as they protect cells from genomic instability. The prominent DSB repair pathway in human cells is the non-homologous end joining (NHEJ) pathway, which mediates template-independent re-ligation of the broken DNA molecule and is active in all phases of the cell cycle. Its role as a guardian of the genome is supported by the fact that defects in NHEJ lead to increased sensitivity to agents that induce DSBs and an increased frequency of chromosomal aberrations. Conversely, evidence from tumors and tumor cell lines has emerged that NHEJ also promotes chromosomal aberrations and genomic instability, particularly in cells that have a defect in one of the other DSB repair pathways. Collectively, the data present a conundrum: how can a single pathway both suppress and promote carcinogenesis? In this review, we will examine NHEJ's role as both a guardian and a disruptor of the genome and explain how underlying genetic context not only dictates whether NHEJ promotes or suppresses carcinogenesis, but also how it alters the response of tumors to conventional therapeutics.

Overview of the Role of Vanillin on Redox Status and Cancer Development

Bioactive natural products play critical roles in modern drug development, especially anticancer agents. It has been widely reported that various pharmacological activities of such compounds are related to their antioxidant properties. Vanillin is a natural substance widely found in many plant species and often used in beverages, foods, cosmetics, and pharmaceutical products. Antioxidant and anticancer potential have been described for this compound. Considering the importance of vanillin in the area of human health and food and pharmaceuticals sectors, in this review, we discuss the role of vanillin on redox status and its potential contribution to the prevention and the treatment of cancer.

Utilization of cytogenetic biomarkers as a tool for assessment of radiation injury and evaluation of radiomodulatory effects of various medicinal plants - a review

Systematic biological measurement of “cytogenetic endpoints” has helped phenomenally in assessment of risks associated with radiation exposure. There has been a surge in recent times for the usage of radioactive materials in health care, agriculture, industrial, and nuclear power sectors. The likelihood of radiation exposure from accidental or occupational means is always higher in an overburdened ecosystem that is continuously challenged to meet the population demands. Risks associated with radiation exposure in this era of modern industrial growth are minimal as international regulations for maintaining the safety standards are stringent and strictly adhered to, however, a recent disaster like “Fukushima” impels us to think beyond. The major objective of radiobiology is the development of an orally effective radio-modifier that provides protection from radiation exposure. Once available for mass usage, these compounds will not only be useful for providing selective protection against accidental and occupational radiation exposure but also help to permit use of higher doses of radiation during treatment of various malignancies curtailing unwarranted adverse effects imposed on normal tissues. Bio-active compounds isolated from natural sources enriched with antioxidants possess unique immune-modulating properties, thus providing a double edged benefit over synthetic radioprotectors. We aim to provide here a comprehensive overview of the various agents originating from plant sources that portrayed promising radioprotection in various experimental models with special emphasis on studies that used cytogenetic biomarkers. The agents will include crude extracts of various medicinal plants, purified fractions, and herbal preparations.

Vanilla--its science of cultivation, curing, chemistry, and nutraceutical properties

Vanilla is a tropical orchid belonging to the family Orchidaceae and it is mainly used in food, perfumery, and pharmaceutical preparations. The quality of the bean depends on the volatile constituent's, viz., the vanillin content, the species of the vine used, and the processing conditions adopted. Hence, proper pollination during flowering and curing by exercising utmost care are the important aspects of vanilla cultivation. There are different methods of curing, and each one is unique and named after the places of its origin like Mexican process and Bourbon process. Recently, Central Food Technological Research Institute, Mysore has developed know-how of improved curing process, where the green vanilla beans are cured immediately after harvest and this process takes only 32 days, which otherwise requires minimum of 150-180 days as reported in traditional curing methods. Vanillin is the most essential component of the 200 and odd such compounds present in vanilla beans. Vanillin as such has not shown any antioxidant properties, it is along with other compounds has got nutraceutical properties and therefore its wide usage. The medicinal future of vanilla may definitely lie in further research on basic science and clinical studies on the constituents and their mechanism of action.

Effect of dietary antioxidants on the cytostatic effect of acrylamide during copper-deficiency in Saccharomyces cerevisiae

Yeast grown on a copper deficient medium was used to study acrylamide toxicity, obviating the need for genetic manipulation and accompanying compensatory effects.

Vanillin protects human keratinocyte stem cells against ultraviolet B irradiation

Ultraviolet-B (UVB) irradiation is one of major factors which induce cellular damages in the epidermis. We investigated protective effects and mechanisms of vanillin, a main constituent of vanilla beans, against UVB-induced cellular damages in keratinocyte stem cells (KSC). Here, vanillin significantly attenuated UVB irradiation-induced cytotoxicity. The vanillin effects were also demonstrated by the results of the senescence-associated β-galactosidase and alkaline comet assays. In addition, vanillin induced production of pro-inflammatory cytokines. Attempts to elucidate a possible mechanism underlying the vanillin-mediated effects revealed that vanillin significantly reduced UVB-induced phosphorylation of ataxia telangiectasia mutated (ATM), serine threonine kinase checkpoint kinase 2 (Chk2), tumor suppressor protein 53 (p53), p38/mitogen-activated protein kinase (p38), c-Jun N-terminal kinase/stress-activated protein kinase (JNK), S6 ribosomal protein (S6RP), and histone 2A family member X (H2A.X). UVB-induced activation of p53 luciferase reporter was also significantly inhibited by vanillin. In addition, while ATM inhibitor had no effect on the vanillin effects, mouse double minute 2 homolog (MDM2) inhibitor significantly attenuated suppressive effects of vanillin on UVB-induced activation of p53 reporter in KSC. Taken together, these findings suggest that vanillin protects KSC from UVB irradiation and its effects may occur through the suppression of downstream step of MDM2 in UVB irradiation-induced p53 activation.

In vitro characterization of glucuronidation of vanillin: identification of human UDP-glucuronosyltransferases and species differences

Vanillin is a food flavoring agent widely utilized in foods, beverages, drugs, and perfumes and has been demonstrated to exhibit multiple pharmacological activities. Given the importance of glucuronidation in the metabolism of vanillin, the UDP-glucuronosyltransferase conjugation pathway of vanillin was investigated in this study. Vanillin glucuronide was identified by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and a hydrolysis reaction catalyzed by β-glucuronidase. The kinetic study showed that vanillin glucuronidation by HLMs and HIMs followed Michaelis-Menten kinetics and the kinetic parameters were as follows: 134.9 ± 13.5 μM and 81.3 ± 11.3 μM for K(m) of HLMs and HIMs, 63.8 ± 2.0 nmol/min/mg pro and 13.4 ±2.0 nmol/min/mg pro for Vmax of HLMs and HIMs. All UDP-glucuronosyltransferase (UGT) isoforms except UGT1A4, 1A9, and 2B7 showed the capability to glucuronidate vanillin, and UGT1A6 exerted the higher V(max)/K(m) values than other UGT isoforms for the glucuronidation of vanillin when assuming expression of isoforms is similar in recombinant UGTs. Kinetic analysis using liver microsomes from six studied speices indicated that vanillin had highest affinity for the monkey liver microsomes enzyme (K(m)  = 25.6 ± 3.2 μM) and the lowest affinity for the mice liver microsomes enzyme (K(m)  = 149.1 ± 18.4 μM), and intrinsic clearance was in the following order: monkey > dog > minipig > mice > rat ~ human. These data collectively provided important information for understanding glucuronidation of vanillin.

AAV-mediated gene targeting is significantly enhanced by transient inhibition of nonhomologous end joining or the proteasome in vivo

Recombinant adeno-associated virus (rAAV) vectors have clear potential for use in gene targeting but low correction efficiencies remain the primary drawback. One approach to enhancing efficiency is a block of undesired repair pathways like nonhomologous end joining (NHEJ) to promote the use of homologous recombination. The natural product vanillin acts as a potent inhibitor of NHEJ by inhibiting DNA-dependent protein kinase (DNA-PK). Using a homology containing rAAV vector, we previously demonstrated in vivo gene repair frequencies of up to 0.1% in a model of liver disease hereditary tyrosinemia type I. To increase targeting frequencies, we administered vanillin in combination with rAAV. Gene targeting frequencies increased up to 10-fold over AAV alone, approaching 1%. Fah(-/-)Ku70(-/-) double knockout mice also had increased gene repair frequencies, genetically confirming the beneficial effects of blocking NHEJ. A second strategy, transient proteasomal inhibition, also increased gene-targeting frequencies but was not additive to NHEJ inhibition. This study establishes the benefit of transient NHEJ inhibition with vanillin, or proteasome blockage with bortezomib, for increasing hepatic gene targeting with rAAV. Functional metabolic correction of a clinically relevant disease model was demonstrated and provided evidence for the feasibility of gene targeting as a therapeutic strategy.

Erythrocyte oxidative damage in rat treated with CCl4

Owing to the presence of hemoglobin and polyunsaturated fatty acids, erythrocytes are a convenient model to understand membrane oxidative damage induced by various xenobiotic pro-oxidants. This study investigated the antioxidant activity of vanillin, a naturally occurring food-flavoring agent, against carbon tetrachloride (CCl4)-induced erythrocyte damages in Wistar albino rats. A single injection of CCl4 (1 ml/kg, intraperitoneally [i.p.]) caused a significant induction of oxidative damage as evidenced by increased thiobarbituric acid reactive substances, protein carbonyl levels and osmotic fragility accompanied with a significant decrease in Na+/K+-ATPase and Ca2+-ATPase activities. Furthermore, catalase and superoxide dismutase activities were significantly elevated, while glutathione levels, glutathione- S-transferase and glutathione peroxidase activities were markedly reduced in the erythrocytes of CCl4-treated rats. Pretreatment of rats with vanillin (150 mg/kg/day, i.p.) for 3 consecutive days before CCl4 injection protected erythrocytes against the increase of lipid peroxidation and degradation of membrane proteins compared to CCl4-treated rats and exhibited marked prevention against CCl4-induced oxidative stress, alterations of membrane-bound enzymes as well as erythrocyte osmotic fragility. Our results suggest that vanillin plays a protective and curative role against the harmful effects of CCl4 on erythrocytes, thus ensuring membrane cell integrity.

Evaluation of genotoxicity in petrol station workers in South India using micronucleus assay

In this study, the micronucleus (MN) frequency was assessed as a measure of genotoxicity in exfoliated cells of buccal mucosa extracted from 110 petrol pump workers and 100 controls. For each individual, 3,000 exfoliated buccal cells were analyzed. The individuals used in the study were grouped based on their smoking, drinking alcoholic beverages, and tobacco chewing habits. There was a significantly higher frequency of micronucleated cells in the exposed workers to petrol than in the unexposed control population. Smoking and drinking (alcohol) habits, age and length of occupation represent significant factors in terms of increasing the MN frequency measured in the exposed population. This study demonstrates that, using MN assay, it is possible to assess the cytogenetic damage in exposed individuals and that the significant increase in the induction of the MN in the exposed population suggests that the studied individuals may be at a higher risk of developing cancer and therefore monitored for any long term adverse effects of the exposure.

Evaluation of Chemical Variability of Cured Vanilla Beans (Vanilla tahitensis and Vanilla planifolia)

In order to establish a chemical fingerprint of vanilla diversity, thirty samples of V. planifolia J. W. Moore and V. tahitensis G. Jackson cured beans from seven producing countries were examined for their aroma and fatty acid contents. Both fatty acid and aroma compositions were found to vary between vanilla species and origins. Vanillin was found in higher amounts in V. planifolia (1.7-3.6% of dry matter) than in V. tahitensis (1.0-2.0%), and anisyl compounds were found in lower amounts in V. planifolia (0.05%) than in V. tahitensis (1.4%-2.1%). Ten common and long chain monounsaturated fatty acids (LCFA) were identified and were found to be characteristic of the vanilla origin. LCFA derived from secondary metabolites have discriminating compositions as they reach 5.9% and 15.8% of total fatty acids, respectively in V. tahitensis and V. planifolia. This study highlights the role of the curing method as vanilla cured beans of two different species cultivated in the same country were found to have quite similar fatty acid compositions.

A comprehensive review on vanilla flavor: Extraction, isolation and quantification of vanillin and others constituents

Vanilla, being the world's most popular flavoring materials, finds extensive applications in food, beverages, perfumery and pharmaceutical industry. With the high demand and limited supply of vanilla pods and the continuing increase in their cost, numerous efforts of blending and adulteration in natural vanilla extracts have been reported. Thus, to ensure the quality of vanilla extracts and vanilla-containing products, it is important to develop techniques to verify their authenticity. Quantitatively, vanillin is the major compound present in the vanilla pods and the determination of vanillin is a vital consideration in natural vanilla extracts. This paper provides a comprehensive account of different extraction processes and chromatographic techniques applied for the separation, identification and determination of chemical constituents of vanilla. The review also provides an account of different methods applied for the quantification and the authentification of chemical constituents of vanilla extract. As the various properties of vanilla are attributed to its main constituent vanillin, its physico-chemical and bioactive properties have also been outlined.

DNA protective properties of vanillin against γ-radiation under different conditions: Possible mechanisms

Ionizing radiation is an important genotoxic agent. Protecting against this form of toxicant, especially by a dietary component, has several potential applications. In the present study, we have examined the ability of vanillin (4-hydroxy-3-methoxybenzaldehyde), a naturally occurring food flavouring agent, to inhibit radiation-induced DNA damage measured as strand breaks under in vitro, ex vivo and in vivo conditions besides the possible mechanisms behind the observed protection. Our study showed that there was a concentration-dependent inhibition of the disappearance of super-coiled (ccc) form of plasmid pBR322 (in vitro) upon exposure to 50 Gy of gamma-radiation. Presence of 0.5 mM vanillin has a dose-modifying factor (DMF) of 6.75 for 50% inactivation of ccc form. Exposure of human peripheral blood leucocytes (ex vivo) to gamma-radiation causes strand breaks in the cellular DNA, as assessed by comet assay. When leucocytes were exposed to 2 Gy of gamma-radiation there was an increase in parameters of comet assay such as %DNA in tail, tail length, 'tail moment' and 'Olive tail moment'. The presence of 0.5 mM vanillin during irradiation significantly reduced these parameters. Damage to DNA in mouse peripheral blood leucocytes after whole-body exposure of mice (in vivo) to gamma-radiation was studied at 1 and 2 h post-irradiation. There was recovery of DNA damage in terms of the above-mentioned parameters at 2 h post-irradiation. This was more than that observed at 1 h. The recovery was more in vanillin treated mice. Hence our studies showed that vanillin offers protection to DNA against radiation-induced damage possibly imparting a role other than modulation of DNA repair. To examine the possible mechanisms of radioprotection, in terms of radiation-derived radicals, we carried out the reaction of vanillin with ABTS*(+) radical spectrophotometrically besides with DNA peroxyl and carbonyl radicals by using pulse radiolysis. Our present investigations show that vanillin has ability to protect against DNA damage in plasmid pBR322, human and mouse peripheral blood leucocytes and splenic lymphocytes besides enhancing survival in splenic lymphocytes against gamma-radiation, and that the possible mechanism may involve scavenging of radicals generated during radiation, apart from modulation of DNA repair observed earlier.

Studies on the antioxidant activities of natural vanilla extract and its constituent compounds through in vitro models

Vanilla extract was prepared by extraction of cured vanilla beans with aqueous ethyl alcohol (60%). The extract was profiled by HPLC, wherein major compounds, viz., vanillic acid, 4-hydroxybenzyl alcohol, 4-hydroxy-3-methoxybenzyl alcohol, 4-hydroxybenzaldehyde and vanillin, could be identified and separated. Extract and pure standard compounds were screened for antioxidant activity using beta-carotene-linoleate and DPPH in vitro model systems. At a concentration of 200 ppm, the extract showed 26% and 43% of antioxidant activity by beta-carotene-linoleate and DPPH methods, respectively, in comparison to corresponding values of 93% and 92% for BHA. Interestingly, 4-hydroxy-3-methoxybenzyl alcohol and 4-hydroxybenzyl alcohol exhibited antioxidant activity of 65% and 45% by beta-carotene-linoleate method and 90% and 50% by DPPH methods, respectively. In contrast, pure vanillin exhibited much lower antioxidant activity. The present study points toward the potential use of vanilla extract components as antioxidants for food preservation and in health supplements as nutraceuticals.

The DNA repair complex DNA-PK, a pharmacological target in cancer chemotherapy and radiotherapy

A line of investigation in the search for sensitizing tumor cells to chemotherapy or radiotherapy relies on the selection of DNA repair inhibitors. In the area of DNA repair mechanisms, DNA-dependent protein kinase (DNA-PK) represents a key complex. Indeed DNA-PK is involved in the non-homologous end joining (NHEJ) process that corresponds to the major activity responsible for cell survival after ionizing radiation or chemotherapeutic treatment producing DNA double strand breaks. DNA-PK belongs to the PI3-K related kinase family and specific inhibitors have been recently selected and evaluated as radio- and chemo-sensitizers. These drugs, along with other ways to inhibit the DSBs repair process, are presented and discussed.

The effect of phenolic and polyphenolic compounds on the development of drug resistance

The effect of two phenolic compounds vanillin (4-hydroxy-3-methoxybenzaldehyde) and lignin on the development of drug/antibiotic resistance in Salmonella typhimurium was studied. Using the modified Ames test we have shown that vanillin alone has negligible effect on spontaneous mutability to ciprofloxacin and gentamicin resistance. At the tested concentrations vanillin reduces the toxicity of 4-nitroquinoline-N-oxide (4NQO) and reduces the ability of this compound to induce mutations leading to ciprofloxacin but not to gentamicin resistance. Lignin at higher concentrations increases mutagenicity to ciprofloxacin resistance and possess considerable inhibition effect on the spontaneous and 4NQO induced mutability to gentamicin resistance.

Vanillin suppresses in vitro invasion and in vivo metastasis of mouse breast cancer cells

Vanillin, a food flavoring agent, has been reported to show anti-mutagenic activity and to inhibit chemical carcinogenesis. In this study, we examined the effect of vanillin on the growth and metastasis of 4T1 mammary adenocarcinoma cells in BALB/c mice. Mice orally administered with vanillin showed significantly reduced numbers of lung metastasized colonies compared to controls. In vitro studies revealed that vanillin, at concentrations that were not cytotoxic, inhibited invasion and migration of cancer cells and inhibited enzymatic activity of MMP-9 secreted by the cancer cells. Vanillin also showed growth inhibitory effect towards cancer cells in vitro. However, vanillic acid, a major metabolic product of vanillin in human and rat, was not active in these in vitro activity assays. Our findings suggest that vanillin has anti-metastatic potential by decreasing invasiveness of cancer cells. Since vanillin is generally regarded as safe, it may be of value in the development of anti-metastatic drugs for cancer treatment.

Vanillins--a novel family of DNA-PK inhibitors

Non-homologous DNA end-joining (NHEJ) is a major pathway of double strand break (DSB) repair in human cells. Here we show that vanillin (3-methoxy-4-hydroxybenzaldehyde)--a naturally occurring food component and an acknowledged antimutagen, anticlastogen and anticarcinogen--is an inhibitor of NHEJ. Vanillin blocked DNA end-joining by human cell extracts by directly inhibiting the activity of DNA-PK, a crucial NHEJ component. Inhibition was selective and vanillin had no detectable effect on other steps of the NHEJ process, on an unrelated protein kinase or on DNA mismatch repair by cell extracts. Subtoxic concentrations of vanillin did not affect the ATM/ATR-dependent phosphorylation of Chk2 or the S-phase checkpoint response after ionising radiation. They significantly potentiated the cytotoxicity of cisplatin, but did not affect sensitivity to UVC. A limited screen of structurally related compounds identified two substituted vanillin derivatives that were 100- and 50-fold more potent than vanillin as DNA-PK inhibitors. These compounds also sensitised cells to cisplatin. The inhibition of NHEJ is consistent with the antimutagenic and other biological properties of vanillin, possibly altering the balance between DSB repair by NHEJ and homologous recombination.

Free radical scavenging activity of vanillin and o-vanillin using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical

Vanillin, a plant derived natural product, used as food flavoring agent and its positional isomer o-vanillin, have been tested for their ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical using high performance liquid chromatography (HPLC). Trolox, a water-soluble analogue of vitamin E and a well-known antioxidant was used as a reference compound. The DPPH radical was monitored at 517 nm and its retention time was 8.6 min. From the decrease in optical density of DPPH radical in the presence of the test compounds, it was observed that o-vanillin was a more effective scavenger than vanillin. At equimolar concentrations (1 mM), vanillin and o-vanillin exhibited 22.9% and 66.4% DPPH radical scavenging activity, respectively. The kinetics of the reaction of vanillin and o-vanillin with DPPH radical was studied using stopped flow spectrophotometry and their rate constants were estimated to be 1.7 +/- 0.1 M(-1)s(-1) and 10.1 +/- 0.8 M(-1)s(-1), respectively. In comparison, the rate constant for the reaction of trolox with DPPH was estimated to be 360.2 +/- 10.1 M(-1)s(-1). These scavenging reactions involve electron/H-atom transfer from antioxidant to DPPH. To confirm this, one electron reduction potentials of these compounds were estimated using cyclic voltammetry which showed that o-vanillin was more easily oxidized than vanillin. The reduction potential for o-vanillin was about 1.5 times that of trolox. These results demonstrate that o-vanillin is a more potent antioxidant than vanillin.

Effect of vanillin on methylene blue plus light-induced single-strand breaks in plasmid pBR322 DNA

The ability of vanillin (4-hydroxy-3-methoxybenzaldehyde), a naturally occurring food flavouring agent, in inhibiting photosensitization-induced single-strand breaks (ssbs) in plasmid pBR322 DNA has been examined in an in vitro system, independent of DNA repair/replication processes. Photosensitization of DNA with methylene blue, visible light and oxygen, induced ssbs resulting in the production of open circular form (OC form) in a concentration-dependent manner. The yield of OC form induced by photosensitization was increased several-fold by deuteration of the buffer and was found to be inhibited by sodium azide, a scavenger of singlet oxygen (1O(2)). Vanillin, per se, did not induce but inhibited photosensitization-induced ssbs in plasmid DNA, at millimolar concentrations. The inhibitory effect of vanillin was both concentration- and time-dependent. On a molar basis, vanillin was, however, less effective than trolox, a water-soluble analogue of alpha-tocopherol. Photosensitization by methylene blue system generates singlet oxygen, as one of the major components of ROS. Therefore, interaction of singlet oxygen with vanillin was investigated. The rate constant of vanillin with 1O(2) was estimated to be 5.93x10(7)M(-1)s(-1) and that of sodium azide as 2. 7x10(8)M(-1)s(-1). The present investigations show that vanillin can protect against photosensitization-induced ssbs in the plasmid pBR322 DNA, and this effect may partly be due to its ability to scavenge 1O(2).

Potentiation by turmeric and curcumin of gamma-radiation-induced chromosome aberrations in Chinese hamster ovary cells

The effect of turmeric and curcumin, two natural antioxidants, on the frequencies of chromosome aberrations induced in Chinese hamster ovary (CHO) cells by gamma-radiation was investigated. Cells were treated with three concentrations of each drug, turmeric (100, 250, and 500 microg/ml) and curcumin (2.5, 5, and 10 microg/ml), and then irradiated (2.5 Gy) during different phases of the cell cycle. Turmeric was not clastogenic by itself, whereas curcumin at 10 microg/ml enhanced the chromosomal damage frequency. Neither of the two antioxidants showed protective effect against the clastogenicity of gamma-radiation. Instead, an obvious increase in the frequencies of chromosome aberrations was observed when turmeric at 500 microg/ml was associated with gamma-radiation during G2/S phase, and curcumin at 10 microg/ml plus gamma-radiation during S and G2/S phases of the cell cycle. The results clearly indicate the exacerbated effect of turmeric and curcumin on radiation-induced clastogenicity, suggesting that these antioxidants are also potentiating agents depending on the experimental conditions.

Vanillin as an antioxidant in rat liver mitochondria: inhibition of protein oxidation and lipid peroxidation induced by photosensitization

Using rat liver mitochondria, as model systems, we have examined the ability of the natural compound and the food-flavoring agent, vanillin to protect membranes against oxidative damage induced by photosensitization at concentrations normally used in food preparations. Vanillin, at a concentration of 2.5 mmol/L, has afforded significant protection against protein oxidation and lipid peroxidation in hepatic mitochondria induced by photosensitization with methylene blue plus light. The effect observed was both time- and concentration-dependent. The inhibitory effect is similar to ascorbic acid and the singlet oxygen quencher, diazabicyclo[2.2.2]octane (DABCO) but less effective than sodium azide and glutathione. Examination of possible mechanisms responsible for the observed protection, showed that vanillin has a significant ability to quench singlet oxygen (1O2), a reactive species responsible for damage induced during photosensitization by Type II mechanism. Hence, this flavoring compound, due to its antioxidant ability, may have potential to prevent oxidative damage to membranes in mammalian tissues and thereby the ensuing diseased states.